Yuuji Kiba, a licensed assassin and expert ninja, is answerable only to Japan's Prime Minister, Itagaki Shigemasa. He's adept at utilizing the Kiba technique, which involves controlling one's muscles, to transform into his alter ego, Kiba Yuuko- a woman who serves as the Prime Minister's covert persona. Together with his mentor, Kiba Sandayuu, Yuuji ensures the Prime Minister's safety by executing secret assassinations, thereby safeguarding Japan and the rest of the world.